Two blocks, joined by a string, have masses of 6 and 9kg. They rest on frictionless horizontal surface. A 2nd string, attached only to the 9kg block, has a horizontal force = 30N applied to it. Both blocks accelerate. Find the tension in the string between the blocks.

Answer 1

Both blocks accelerate at the same rate. Draw free body diagrams and write Newton's second law (F = ma) for each block. Solve for the two unknowns: accleration and string tension.